1. Technical Field
This invention relates generally to trailer hitches and more particularly to shock absorbing trailer hitches. More particularly, the present invention relates to a trailer hitch that minimizes the transmission of shock forces between a towing vehicle and a towed vehicle. Specifically, the invention relates to such a shock absorbing trailer hitch in which pivotal movement of the trailer hitch is absorbed by a shock absorbing mechanism.
2. Background Information
Various types of hitches and towing configurations are known in the art. Three typical trailer hitch configurations are generally known as receiver hitches, gooseneck hitches, and fifth wheel hitches. A receiver hitch typically extends beyond the rear bumper of the towing vehicle while gooseneck and fifth wheel hitches are disposed in the bed of the towing vehicle in front of the rear bumper. A problem common to all of these hitches is the transmission forces from the tow vehicle to the towing vehicle. Shock absorbing trailer hitches are generally known in the art for reducing the transfer of these forces. Several examples of such a shock absorbing hitch is disclosed in U.S. Pat. No. 5,683,094 granted to Gullickson. Gullickson discloses several embodiments each of which is configured to absorb forces in all directions. Each of these embodiments is configured with a socket mountable on a hitch ball which is rigidly mounted on the towing vehicle. One of the embodiments includes a larger diameter cylindrical shaft which is rigidly mounted on the socket and extends vertically upwardly therefrom with a smaller diameter cylindrical shaft mounted atop the larger diameter shaft. The smaller diameter shaft extends through an upper energy absorbing pad which mounts the cylindrical shafts to the towed vehicle in a manner which allows the shafts and socket to move vertically and to pivot about the upper elastomeric energy absorbent pad in all directions with respect to the towed vehicle. A cylindrical housing is rigidly mounted to the towed vehicle with an annular elastomeric energy absorbing pad disposed within the housing with the larger diameter cylindrical shaft extending through the central hole of the pad. Pivotal movement of the larger shaft is absorbed by the annular pad.
This embodiment of Gullickson is configured specifically for a gooseneck hitch and is not suitable for a receiver hitch where the socket of a trailer tongue is mounted directly to a hitch ball. In addition, the pivotal connection between the smaller diameter shaft and the towed vehicle via the upper elastomeric pad presents a concern over undue wear of the upper elastomeric pad over time.
In addition, a shock absorbing trailer hitch manufactured by TrailerSaver of Davison, Mich. utilizes pneumatic shock absorbers. More particularly, TrailerSaver makes shock absorbing hitches adapted for use with a fifth wheel or goose neck connection. The primary drawback of the TrailerSaver hitches is the use of a pneumatic system, which requires associated apparatus in order to pressurize the pneumatic shock absorbers. For example, such pneumatic shock absorbers require pneumatic conduits and valves which may either be connected with a pneumatic system of a vehicle or to a compressor which is additionally provided for vehicles not having such a pneumatic system. The pneumatic shock absorbers and the associated equipment is susceptible to damage requiring the replacement thereof. In addition, the assembly of the pneumatic trailer hitches with a vehicle's pneumatic system requires additional assembly time.
Thus, there is room for improvement with regard to a shock absorbing trailer hitch wherein the hitch provides pivotal movement between the towing vehicle and the towed vehicle.